EP2399633A1

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Info

Publication number: EP2399633A1
Application number: EP10167501A
Authority: EP
Inventors: designation of the inventor has not yet been filed The
Original assignee: Sanofi Aventis Deutschland GmbH
Current assignee: Sanofi Aventis Deutschland GmbH
Priority date: 2010-06-28
Filing date: 2010-06-28
Publication date: 2011-12-28
Also published as: EP2585136B1; US20130296794A1; JP2013529527A; CA2803038A1; WO2012000941A3; DK2585136T3; US9492622B2; WO2012000941A2; JP5914472B2; EP2585136A2

Abstract

The invention refers to a needle safety arrangement for protecting a hollow injection needle (4) of a syringe (3) after an injection, the needle safety arrangement comprising:
- a needle sheath (11) having essentially the shape of a hollow cylinder arranged to surround the needle (4), the needle sheath slidable in longitudinal direction with respect to the syringe (3) and biased in proximal direction (P),
- a sheath linkage (12), slidable in longitudinal direction,
- a syringe carrier (7) for holding the syringe (3), the syringe (3) and syringe carrier (7) arranged for joint axial translation and rotation relative to the needle sheath (11), wherein the sheath linkage (12) comprises means (12.3) for restricting translation in proximal direction (P) with respect to the syringe (3) by abutting against the syringe carrier (11), wherein in an initial state the sheath linkage (12) is abutted against the syringe carrier (7) and latched to the needle sheath (11) for joint axial translation, wherein the syringe carrier (7) exhibits at least one cam (7.4) on its circumference, wherein the cam (7.4) is arranged to de-latch the needle sheath (11) from the sheath linkage (12) on rotation of the syringe carrier (7) so as to release the needle sheath (11) for being translated in proximal direction (P) and cover the needle (4).

Description

Technical Field

The invention relates to a needle safety arrangement and to a method for operating it.

Background of the Invention

Administering an injection is a process which presents a number of risks and challenges for users and healthcare professionals, both mental and physical.

Injection devices (i.e. devices capable of delivering medicaments from a medication container) typically fall into two categories - manual devices and auto-injectors.

In a manual device - the user must provide the mechanical energy to drive the fluid through the needle. This is typically done by some form of button / plunger that has to be continuously pressed by the user during the injection. There are numerous disadvantages for the user from this approach. If the user stops pressing the button /plunger then the injection will also stop. This means that the user can deliver an underdose if the device is not used properly (i.e. the plunger is not fully pressed to its end position). Injection forces may be too high for the user, in particular if the patient is elderly or has dexterity problems.

The extension of the button/plunger may be too great. Thus it can be inconvenient for the user to reach a fully extended button. The combination of injection force and button extension can cause trembling / shaking of the hand which in turn increases discomfort as the inserted needle moves.

Auto-injector devices aim to make self-administration of injected therapies easier for patients. Current therapies delivered by means of self-administered injections include drugs for diabetes (both insulin and newer GLP-1 class drugs), migraine, hormone therapies, anticoagulants etc.

Auto-injectors are devices which completely or partially replace activities involved in parenteral drug delivery from standard syringes. These activities may include removal of a protective syringe cap, insertion of a needle into a patient's skin, injection of the medicament, removal of the needle, shielding of the needle and preventing reuse of the device. This overcomes many of the disadvantages of manual devices. Forces required of the user / button extension, hand-shaking and the likelihood of delivering an incomplete dose are reduced. Triggering may be performed by numerous means, for example a trigger button or the action of the needle reaching its injection depth. In some devices the energy to deliver the fluid is provided by a spring.

Auto-injectors may be disposable or single use devices which may only be used to deliver one dose of medicament and which have to be disposed of after use. Other types of auto-injectors may be reusable. Usually they are arranged to allow a user to load and unload a standard syringe. The reusable auto-injector may be used to perform multiple parenteral drug deliveries, whereas the syringe is disposed after having been spent and unloaded from the auto-injector. The syringe may be packaged with additional parts to provide additional functionality.

US 2002/0095120 A1 discloses an automatic injection device which automatically injects a pre-measured quantity of fluid medicine when a tension spring is released. The tension spring moves an ampoule and the injection needle from a storage position to a deployed position when it is released. The content of the ampoule is thereafter expelled by the tension spring forcing a piston forward inside the ampoule. After the fluid medicine has been injected, energy stored in the tension spring is released and the injection needle is automatically retracted back to its original storage position.

Summary of the Invention

It is an object of the present invention to provide an improved needle safety arrangement for protecting a hollow injection needle of a syringe after an injection.
It is another object of the present invention to provide an improved method for operating a needle safety arrangement.
The object is achieved by a needle safety arrangement according toclaim 1 and by a method according toclaim 12.
Preferred embodiments of the invention are given in the dependent claims.
In the context of this specification the term proximal refers to the direction pointing towards the patient during an injection while the term distal refers to the opposite direction pointing away from the patient. The terms "clockwise" and "counter-clockwise" in the context of this specification refer to senses of rotation with the auto-injector pointing with its distal end towards the observer.
According to the invention a needle safety arrangement for protecting a hollow injection needle of a syringe after an injection comprises:

a needle sheath having essentially the shape of a hollow cylinder arranged to surround the needle, the needle sheath slidable in longitudinal direction with respect to the syringe and biased in proximal direction,
a sheath linkage, slidable in longitudinal direction,
a syringe carrier for holding the syringe, the syringe and syringe carrier arranged for joint axial translation and rotation relative to the needle sheath.

The sheath linkage comprises means for restricting translation in proximal direction with respect to the syringe. The means may be a collar or a shoulder abutting distally against the syringe carrier. In an initial state the sheath linkage is abutted against the syringe carrier and latched to the needle sheath for joint axial translation. The syringe carrier exhibits at least one cam on its circumference. The cam is arranged to de-latch the needle sheath from the sheath linkage on rotation of the syringe carrier so as to release the needle sheath for being translated in proximal direction and cover the needle. In an injection cycle the syringe and syringe carrier have to be translated in proximal direction so as to insert the needle into an injection site, e.g. a patient's skin. The rotation of the syringe carrier required for de-latching the needle sheath from the sheath linkage may occur during this translation.
The syringe carrier may exhibit at least one slot on its circumference. The latched needle sheath and sheath linkage may form at least one spline, each spline arranged for engaging one of the slots in the initial position so as to prevent rotation of the syringe carrier. The spline may be arranged to be disengaged from the slot on translation of the needle sheath in distal direction from the initial position. This avoids premature release of the needle sheath. Instead, the needle sheath has first to be translated in distal direction, e.g. by being pressed against the injection site.
The syringe carrier may be arranged to be rotated by at least one ramp on translation from an initial distal position in proximal direction so as to de-latch the needle sheath from the sheath linkage. The ramp may be arranged on the syringe carrier and/or on a housing or main body in which the syringe carrier rotates. Due to the ramp the syringe carrier can neither translate when prevented from rotating nor rotate when not translated. The syringe carrier, the syringe and the needle can therefore not translate for inserting the needle unless the needle sheath is pushed from its initial position in distal direction since the spline otherwise prevents rotation of the syringe carrier.
The needle sheath may comprise at least one sheath leg extending from the needle sheath in distal direction. The sheath linkage may comprise at least one linkage leg. The spline consists of a distal end portion of the sheath leg and a proximal end portion of the linkage leg. A rib may protrude inwards from the distal end of the sheath leg. The rib has an aperture for accommodating the proximal end of the linkage leg. The proximal end portion of the linkage leg comprises an inwardly biased resilient tongue connected to the linkage leg at one end and with the other free end engaged proximally behind the rib in the initial position so as to prevent removal of the proximal end portion of the linkage leg through the aperture in the rib. The sheath linkage and the needle sheath are thus latched together. The tongue is arranged to be flexed outwards by the cam on rotation of the syringe carrier so as to align it with the linkage leg and allow the linkage leg to be at least partially pulled out of the aperture in the rib thus de-latching the needle sheath and the sheath linkage. Preferably, at least two or three linkage leg and sheath legs may be provided.
The needle safety arrangement may be applied in a manual injection arrangement or in an auto-injector for administering a dose of a liquid medicament. The auto-injector may have a distal end and a proximal end with an orifice intended to be applied against an injection site. Furthermore, the auto-injector may comprise:

an elongate housing arranged to contain a syringe with a hollow needle and a stopper for sealing the syringe and displacing the medicament, wherein the syringe is slidably arranged with respect to the housing,
a drive means capable of, upon activation:
- pushing the needle from a retracted position into an advanced position through the orifice and past the proximal end, and
- operating the syringe to supply the dose of medicament,
a plunger for transmitting power from the drive means to the syringe and/or stopper,
activating means arranged to lock the drive means in a compressed state prior to manual operation and capable of, upon manual operation, releasing the drive means for injection.

The auto-injector according to the invention has a particularly low part count compared to most conventional auto-injectors.
In a preferred embodiment the drive means is a compression spring distally grounded in the housing and proximally pushing on the plunger. The plunger is arranged to be rotated by at least one ramp on translation from an initial distal position in proximal direction similarly to the rotation of the syringe holder. A distal wide end of the linkage arm is arranged to engage the plunger in a manner to prevent rotation and thus translation of the plunger in the initial state. In the initial state the needle sheath is in its initial position protruding beyond a proximal end of the housing. The wide end is furthermore arranged to disengage from the plunger on translation of the needle sheath and sheath linkage in distal direction from the initial position. Thus, in order to start an injection cycle, the needle sheath has to be pressed against the injection site. Consequently, the needle sheath and the sheath linkage translate in distal direction thereby disengaging the syringe carrier from the spline and the plunger from the distal wide end of the linkage arm and allowing them to rotate. Due to the ramp the plunger can neither translate when prevented from rotating nor rotate when not translated. Therefore the plunger cannot translate for inserting the needle unless being disengaged from the distal wide end of the sheath linkage.
The auto-injector may be configures to release the drive spring and plunger immediately when the needle sheath is pushed in distal direction. In this case the needle sheath and sheath linkage serve as the activating means.
Preferably the activating means comprises a trigger button arranged to be engaged with the plunger so as to prevent rotation and thus translation of the plunger prior to operation. The trigger button is arranged to be disengaged from the plunger when operated. Starting an injection thus requires two actions: pressing the needle sheath against the injection site and operating the trigger button. This reduces the risk for inadvertently triggering the auto-injector.
The angles and widths of the ramps for rotating the syringe carrier and the plunger are preferably matched so as to rotate the plunger, the syringe and the syringe carrier as a single body.
In a preferred embodiment rotation of the syringe by the ramps stops before the needle protrudes from the proximal end of the housing or from the needle sheath. The subsequent motion of the syringe and needle is purely linear so the needle does not screw into the injection site.
At least one resilient latch may be arranged on the circumference of the syringe carrier for flexing outwards into a respective recess in the housing when the syringe carrier, syringe and needle have been translated in proximal direction and the needle has reached a predefined injection depth. The latch may likewise be arranged on the housing and the recess in the syringe carrier.
In another preferred embodiment at least one inwardly biased resilient snap may be arranged near the proximal end in the housing for preventing the needle sheath from translating in distal direction after having been translated into a proximal position for covering the needle. The needle can therefore not be re-exposed after injection.
A method for operating a needle safety arrangement for protecting a hollow injection needle of a syringe after an injection comprises:

restricting translation of the sheath linkage in proximal direction in the initial state, wherein the sheath linkage is latched to the needle sheath for joint axial translation,
rotating the syringe carrier, thereby de-latching the needle sheath from the sheath linkage by means of at least one cam arranged on the circumference of the syringe carrier so as to release the needle sheath for being translated in proximal direction and cover the needle.

In the initial position the at least one spline formed by the latched needle sheath and sheath linkage is engaged in the respective slot on the circumference of the syringe carrier so as to prevent rotation of the syringe carrier. In order to allow rotation of the syringe carrier the needle sheath is translated in distal direction from the initial position thereby disengaging the spline from the slot.
The auto-injector may have at least one viewing window for inspecting the syringe.
The auto-injector may preferably be used for subcutaneous or intra-muscular injection, particularly for delivering one of an analgetic, an anticoagulant, insulin, an insulin derivate, heparin, Lovenox, a vaccine, a growth hormone, a peptide hormone, a proteine, antibodies and complex carbohydrates.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief Description of the Drawings

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

Figure 1: is an isometric partial sectional view of an auto-injector in an initial state,
Figure 2: is a longitudinal section of the auto-injector in the initial state,
Figure 3: is a longitudinal partial section of the auto-injector in the initial state,
Figure 4: are three detail views of the auto-injector,
Figure 5: is an isometric partial sectional view of the auto-injector with a needle sheath translated into the auto-injector,
Figure 6: is a longitudinal section of the auto-injector in the state as infigure 5,
Figure 7: is a longitudinal partial section of the auto-injector in the state as infigure 5,
Figure 8: is an isometric partial sectional view of the auto-injector with the needle inserted into an injection site at the end of an injection,
Figure 9: is a longitudinal section of the auto-injector in the state as infigure 8,
Figure 10: is a longitudinal partial section of the auto-injector in the state as infigure 8,
Figure 11: is an isometric partial sectional view of the auto-injector with the needle sheath advanced after injection,
Figure 12: is a longitudinal section of the auto-injector in the state as infigure 11,
Figure 13: is a longitudinal partial section of the auto-injector in the state as infigure 11, and
Figure 14: is a detail of a proximal end of the auto-injector with the needle sheath advanced and snapped to thehousing 2.

Corresponding parts are marked with the same reference symbols in all figures.

Detailed Description of Preferred Embodiments

Figures 1, 2 and3 show an auto-injector 1 in an initial state or as delivered configuration. The auto-injector comprises anelongate housing 2 having a distal portion 2.1 and a proximal portion 2.2 telescoped into each other and connected by a snap fit 2.3. Asyringe 3, e.g. a Hypak syringe, with a hollow needle 4 is arranged in the proximal portion 2.2 of the auto-injector 1. When the auto-injector 1 or thesyringe 3 is assembled a protective needle shield may be attached to the needle (not illustrated). Astopper 6 is arranged for sealing thesyringe 3 distally and for displacing a liquid medicament M through the hollow needle 4. Thesyringe 3 is held in atubular syringe carrier 7 and supported at its proximal end therein. Asingle drive spring 8 in the shape of a compression spring is arranged in the distal portion 2.1 of the auto-injector 1. Aplunger 9 is arranged for forwarding the load of thedrive spring 8 to thesyringe 3 and/or to thestopper 6. Atrigger button 10 is laterally arranged on thehousing 2, thetrigger button 10 having the shape of a rocker pivoted in a transversal axle 10.1 on thehousing 2. In the initial state a distal arm 10.2 of the trigger button projects inwards through an aperture in thehousing 2 in a manner to prevent thedrive spring 8 from expanding. A proximal arm 10.3 of thetrigger button 10 protrudes radially outward, preferably sprung by a resilient element 10.4. Aneedle sheath 11 having essentially the shape of a hollow cylinder is telescoped in a proximal end P of thehousing 2 and protruding from thehousing 2 in the initial state. Three sheath legs 11.1 extend from theneedle sheath 11 in distal direction D.A sheath linkage 12 is arranged distally from the sheath legs 11.1 for interacting with the sheath legs 11.1 in a manner described below. Thesheath linkage 12 comprises a number of linkage legs 12.1 extending in longitudinal direction. Theplunger 9 comprises a piston rod 9.1 having an enlarged distal face 9.2 and a hollow plunger cylinder 9.3 attached to the distal face 9.2.

In the initial state thedrive spring 8 in the shape of a compression spring is held compressed between a distal face 2.4 of thehousing 2 and a collar 9.4 on theplunger 9. The collar 9.4 is an incomplete collar with at least one circumferential gap 9.5 (cf.figs 5,7,8,10,11,13). An edge of the collar 9.4 towards one of the circumferential gaps 9.5 is shaped as a first ramp 9.6 arranged to interact with a corresponding second ramp 2.5 on thehousing 2 in a manner to rotate theplunger 9 on translation from its initial distal position in proximal direction P. At least one of the linkage legs 12.1 has a distal wide end 12.4 arranged to fill one of the circumferential gaps 9.5 so as to prevent rotation and thus translation of theplunger 9 in the initial state. Furthermore, the distal arm 10.2 of thetrigger button 10 is engaged in one of the circumferential gaps 9.5 in a manner to prevent rotation of the plunger 9 (not illustrated).
Thesyringe carrier 7 has two circumferential third and fourth ramps 7.1, 7.2 engaged with two corresponding fifth and sixth ramps 2.6, 2.7 in thehousing 2 so as to rotate thesyringe carrier 7 on translation in proximal direction P. The sixth ramp 2.7 provides a backstop to prevent movement of thesyringe carrier 7 in the distal direction D. In the initial state counter-clockwise rotation (seen from the distal end D) and hence translation in proximal direction P is prevented by a series of three splines created by theneedle sheath 11 andsheath linkage 12. One of the splines is shown infigures 4a, b, c). The other two splines are angularly spaced from the one infigure 4, preferably equally distributed over the circumference of thesyringe carrier 7. Each spline consists of a distal end portion of one of the sheath legs 11.1 and a proximal end portion of one of the linkage legs 12.1. The sheath leg 11.1 exhibits a rib 11.2 protruding inwards from the distal end of the sheath leg 11.1, the rib 11.2 having an aperture for accommodating the proximal end portion of the linkage leg 12.1. The proximal end portion of the linkage leg 12.1 comprises a resilient tongue 12.2 connected to the linkage leg 12.1 near its proximal tip, extending in distal direction D and biased inwards so that it protrudes inwardly unless it is flexed into an aperture in the linkage leg 12.1. When the proximal end portion of the linkage leg 12.1 is held in the aperture of the rib 11.2 with a stop 12.5 on the linkage leg 12.1 abutting against the rib 11.2 of the sheath leg 11.1 as infigures 4 a and b the inwardly protruding tongue 12.2 cannot return through the rib 11.2 and locks the sheath leg 11.1 to the linkage leg 12.1 for joint axial translation. In the initial position shown infigure 4a the rib 11.2 is engaged with a slot 7.3 in thesyringe carrier 7 so as to prevent counter-clockwise rotation.
Translation of thesyringe carrier 7 in distal direction D and clockwise rotation are prevented by the sixth ramp 2.7 on the proximal portion 2.2 (cf.fig. 2).
In order to start an injection cycle the auto-injector 1 has to be pushed against an injection site, e.g. a patient's skin. Thus theneedle sheath 11 is translated from a proximal position into thehousing 2 in distal direction D. Furthermore, thetrigger button 10 has to be pressed in order to release thedrive spring 8.
Theneedle sheath 11 is biased in proximal direction P by aneedle sheath spring 13 and prevented from moving too far forwards by a collar 12.3 of thesheath linkage 12 which references off a distal face of thesyringe carrier 7. In the initial position theneedle sheath 11 and thesheath linkage 12 are connected for joint axial motion (cf.figures 4a, b) so the collar 12.3 of thesheath linkage 12 abutting against the distal face of the syringe carrier keeps theneedle sheath 11 from advancing. By placing the auto-injector 1 against the injection site and pushing theneedle sheath 11 in distal direction D (seefigures 5,6 and 7) the distal end of the spline which is thicker due to the rib 11.2 and due the distally adjacent part of the linkage leg 12.1 (cf.fig. 4a) is moved in distal direction D relative to the slot 7.3 in thesyringe carrier 7 and replaced by a thinner portion of the spline proximally from the rib 11.2 (cf.fig. 4b). The spline is no longer engaged with the slot 7.3 so thesyringe carrier 7 can now rotate about the third and fifth ramps 7.1, 2.6 on the inside of the proximal portion 2.2 and translate in proximal direction P if driven by thedrive spring 8. The low force of theneedle sheath spring 13 biasing theneedle sheath 11 against thesyringe carrier 7 holds thesyringe 3 andsyringe carrier 7 back until thedrive spring 8 is released.
If the auto-injector 1 is removed from the injection site in this situation without pushing thetrigger button 10, theneedle sheath 11 and thesheath linkage 12 would return into their initial position as infigures 1, 2 and3. The ramp on the distal wide end 12.4 ensures that thesheath linkage 12 is guided back to its initial position. The thicker distal end of the spline would re-engage with the slot 7.3, returning the auto-injector 1 to its initial state.
With theneedle sheath 11 pressed against the injection site and held in its distal position thesyringe carrier 7 is free to rotate counter-clockwise and translate in proximal direction P. Furthermore, the distal wide end 12.4 of the linkage leg 12.1 is translated in distal direction D until an edge of the gap 9.5 is no longer engaged with the linkage leg 12.1 (cf.fig. 7). Rotation of theplunger 9 is now only prevented by the distal arm 10.2 of thetrigger button 10 engaged in the gap 9.5.
In order to trigger the auto-injector 1 the user must push the proximal arm 10.3 of thetrigger button 10 inwards. The distal arm 10.2 projecting into the gap 9.5 in theplunger 9 is pulled out of the gap 9.5. Thedrive spring 8 pushes on the collar 9.4 of theplunger 9 thus translating theplunger 9 in proximal direction P and rotating it counter-clockwise due to the first ramp 9.6 of theplunger 9 sliding along the second ramp 2.5 on thehousing 2. The piston rod 9.1 of theplunger 9 pushes on thestopper 6 of thesyringe 3. As the force required to eject the liquid medicament M from the syringe is significantly higher than the force required to move thesyringe 3 in proximal direction P, thesyringe 3 translates in proximal direction P and the needle 4 is inserted into the injection site. As thesyringe 3 translates thesyringe carrier 7 translates with it and rotates counter-clockwise at the same time due to the engagement of the third and fifth ramps 7.1, 2.6.
As thesyringe carrier 7 rotates, a cam 7.4 on the circumference of thesyringe carrier 7 arranged clockwise from the slot 7.3 pushes the tongue 12.2 outwards into the aperture of the linkage leg 12.1 thus allowing the sheath leg 11.1 and the linkage leg 12.1 to separate and move independently.
The angles and widths of the ramps 9.6, 2.5, 2.6, 2.7, 7.1, 7.2 are matched so as to rotate theplunger 9, thesyringe 3 and thesyringe carrier 7 as a single body while theneedle sheath 11 and thesheath linkage 12 do not rotate relative to thehousing 2. This rotation completes before the needle 4 protrudes from the proximal end P of thehousing 2. The remaining motion of theplunger 9, thesyringe carrier 7, thesyringe 3 and the needle 4 in proximal direction P until reaching an injection depth is a purely linear translation so the needle 4 does not screw into the injection site.
The injection depth is controlled by at least one resilient latch 7.5 on the circumference of thesyringe carrier 7 flexing out into a recess 2.9 (cf.figs. 2,3,6, 7) in thehousing 2 on translation of thesyringe carrier 7 and abutting against a proximal edge of this recess 2.9. As thesyringe carrier 7 translates theneedle sheath spring 13 is compressed.
As thesyringe 3 stops translating the piston rod 9.1 continues translating and pushes thestopper 6 in proximal direction P thus injecting the liquid medicament M through the hollow injection needle 4 into the injection site, i.e. into or through the patient's skin.
Figures 8, 9 and10 show the auto-injector 1 at the end of the injection. Thestopper 6 has bottomed out in thesyringe 3 and injected the entire contents of thesyringe 3 into the injection site.
When the auto-injector 1 is removed from the injection site during or at the end of injection theneedle sheath 11 translates in proximal direction P due to the force of theneedle sheath spring 13 into a proximal position (seefigures 11,12 and 13). Since the sheath leg 11.1 and the linkage leg 12.1 have been separated by the cam 7.4 disengaging the tongue 12.2, translation of theneedle sheath 11 in proximal direction P is no longer restricted by thesheath linkage 12. Instead theneedle sheath 11 is translated into a position where it protrudes even more from thehousing 2 than in the initial state until the rib 11.2 of the sheath leg 11.1 abuts against the distal face of thesyringe carrier 7 as infigure 4c.
When theneedle sheath 11 is translated far enough in proximal direction P to protect the user from the needle 4, inwardly biased resilient snaps 2.10 in the proximal portion 2.2 are pushed out by the translatingneedle sheath 11 and then move inwards permanently preventing theneedle sheath 11 from moving back into thehousing 2 in distal direction D (see details infigure 14).
In the illustrated embodiment thetrigger button 10 may be pressed before or after translation of theneedle sheath 11 in distal direction D in the initial state or even at the same time. Optionally, thesheath linkage 12 may be interlocked with thetrigger button 10 so as to require a sequence of operation wherein thesheath linkage 12 has to be translated into the auto-injector 1 before thetrigger button 10 can be pressed.
The counter-clockwise sense of rotation of theplunger 9 and thesyringe carrier 7 have been arbitrarily chosen in the above embodiment. In an alternative embodiment theplunger 9 and/or thesyringe carrier 7 may be arranged to rotate clockwise due to a different arrangement of the ramps 9.6, 2.5, 2.6, 2.7, 7.1, 7.2.
Instead of the pairs of ramps 9.6 and 2.5, 7.1 and 2.6, 7.2 and 2.7 it would be sufficient to provide a ramp on just one of the involved components engaged with a follower on the respective other component.
The auto-injector 1 of the above embodiment exhibits three sheath legs 11.1 and linkage legs 12.1. Likewise, another number could be chosen.
In an alternative embodiment the auto-injector 1 may be arranged to rotate theplunger 9, thesyringe carrier 7, thesyringe 3 and the needle 4 until reaching the injection depth even during needle insertion.
The rib 11.2 may be likewise arranged on the linkage leg 12.1 with the distal portion of the sheath leg 11.1 extending through the aperture in the rib and the tongue being part of the sheath leg 11.1.
Figures 5 to 10 show theneedle sheath 11 flush with the proximal end P of thehousing 2 for triggering an injection. It is likewise possible to disengage the spline from the slot 7.3 and the distal wide end 12.4 from the gap 9.5 when theneedle sheath 11 is still slightly protruding from thehousing 2.
Optionally thesyringe 3 may be arranged for joint axial movement with a syringe holder slidably arranged in thehousing 2. The syringe holder may be provided with at least two resilient syringe holder arms arranged distally, the syringe holder arms having a respective inclined surface for bearing against a shoulder in the piston rod 9.1. The syringe holder arms may be supportable by an inner surface of thehousing 2 in order to prevent them from being flexed outward. Thus, when thedrive spring 8 is released the spring force forwarded by the piston rod 9.1 of theplunger 9 does not yet press against thestopper 6 but against thesyringe 3 for forwarding it. Consequently, a so called wet injection is avoided, i.e. the liquid medicament M is not leaking out of the hollow needle 4 before the needle 4 is inserted. A widened portion may be provided in thehousing 2 for allowing the syringe holder arms to flex outwards when the syringe holder has nearly reached a maximum proximal position thus allowing the shoulder in the piston rod 9.1 to slip through the syringe holder arms and to switch load of thedrive spring 8 from thesyringe 3 to thestopper 6. This allows for defining the moment to start injecting the medicament M.

List of References

1: auto-injector
2: housing
2.1: distal portion
2.2: proximal portion
2.3: snap fit
2.4: distal face
2.5: second ramp
2.6: fifth ramp
2.7: sixth ramp
2.8: stop
2.9: recess
2.10: snap
3: syringe
4: needle
6: stopper
7: syringe carrier
7.1: third ramp
7.2: fourth ramp
7.3: slot
7.4: cam
7.5: resilient latch
8: drive spring, drive means, compression spring
9: plunger
9.1: piston rod
9.2: distal face
9.3: plunger cylinder
9.4: collar
9.5: circumferential gap
9.6: first ramp
9.7: distal corner
10: trigger button
10.1: transversal axle
10.2: distal arm
10.3: proximal arm
10.4: resilient element
11: needle sheath
11.1: sheath leg
11.2: rib
12: sheath linkage
12.1: linkage leg
12.2: tongue
12.3: collar
12.4: wide end
12.1: stop
13: needle sheath spring
D: distal end, distal direction
M: medicament
P: proximal end, proximal direction

Claims

Needle safety arrangement for protecting a hollow injection needle (4) of a syringe (3) after an injection, the needle safety arrangement comprising:
- a needle sheath (11) having essentially the shape of a hollow cylinder arranged to surround the needle (4), the needle sheath slidable in longitudinal direction with respect to the syringe (3) and biased in proximal direction (P),
- a sheath linkage (12), slidable in longitudinal direction,
- a syringe carrier (7) for holding the syringe (3), the syringe (3) and syringe carrier (7) arranged for joint axial translation and rotation relative to the needle sheath (11),
wherein the sheath linkage (12) comprises means for restricting translation in proximal direction (P) with respect to the syringe (3) by abutting against the syringe carrier (11), wherein in an initial state the sheath linkage (12) is abutted against the syringe carrier (7) and latched to the needle sheath (11) for joint axial translation, wherein the syringe carrier (7) exhibits at least one cam (7.4) on its circumference, wherein the cam (7.4) is arranged to de-latch the needle sheath (11) from the sheath linkage (12) on rotation of the syringe carrier (7) so as to release the needle sheath (11) for being translated in proximal direction (P) and cover the needle (4).
Needle safety arrangement according to claim 1,characterized in that the syringe carrier exhibits at least one slot (7.3) on its circumference and that the latched needle sheath (11) and sheath linkage (12) form at least one spline, each spline arranged for engaging one of the slots (7.3) in the initial position so as to prevent rotation of the syringe carrier (7), wherein the spline is arranged to be disengaged from the slot (7.3) on translation of the needle sheath (11) in distal direction (D) from the initial position.
Needle safety arrangement according to one of the claims 1 or 2,characterized in that the syringe carrier (7) is arranged to be rotated by at least one ramp (2.6, 7.1) on translation from an initial distal position in proximal direction (P) so as to de-latch the needle sheath (11) from the sheath linkage (12).
Needle safety arrangement according to one of the preceding claims,characterized in that the needle sheath (11) comprises at least one sheath leg (11.1) extending from the needle sheath (11) in distal direction (D), wherein the sheath linkage (12) comprises at least one linkage leg (12.1), wherein the spline consists of a distal end portion of the sheath leg (11.1) and a proximal end portion of the linkage leg (12.1), wherein a rib protrudes inwards from the distal end of the sheath leg (11.1), the rib (11.2) having an aperture for accommodating the proximal end of the linkage leg (12.1), wherein the proximal end portion of the linkage leg (12.1) comprises an inwardly biased resilient tongue (12.2) connected to the linkage leg (12.1) at one end and with the other free end engaged proximally behind the rib (11.2) in the initial position so as to prevent removal of the proximal end portion of the linkage leg (12.1) through the aperture in the rib (11.2), wherein the tongue (12.2) is arranged to be flexed outwards by the cam (7.4) on rotation of the syringe carrier (7) so as to align it with the linkage leg (12.1) and allow the linkage leg (12.1) to be at least partially pulled out of the aperture in the rib (11.2).
Auto-injector (1) for administering a dose of a liquid medicament (M), the auto-injector (1) having a distal end (P) and a proximal end (D) with an orifice intended to be applied against an injection site and comprising:
- an elongate housing (2) arranged to contain a syringe (4) with a hollow needle (5) and a stopper (6) for sealing the syringe (4) and displacing the medicament (M), wherein the syringe (4) is slidably arranged with respect to the housing (2),
- a drive means (8) capable of, upon activation:
- pushing the needle (5) from a retracted position into an advanced position through the orifice and past the proximal end (P), and
- operating the syringe (4) to supply the dose of medicament (M),
- a plunger (7) for transmitting power from the drive means (8) to the syringe (4) and/or stopper (6),
- activating means arranged to lock the drive means (8) in a compressed state prior to manual operation and capable of, upon manual operation, releasing the drive means (8) for injection, and
- a needle safety arrangement according to one of the preceding claims.
Auto-injector (1) according to claim 5,characterized in that the drive means (8) is a compression spring (8) distally grounded in the housing (2) and proximally pushing on the plunger (9), wherein the plunger (9) is arranged to be rotated by at least one ramp (9.6, 2.5) on translation from an initial distal position in proximal direction (P), wherein a distal wide end (12.4) of the linkage arm (12.1) is arranged to engage the plunger (9) in a manner to prevent rotation and thus translation of the plunger (9) in the initial state, wherein in the initial state the needle sheath (11) is in its initial position protruding beyond a proximal end of the housing (2), wherein the wide end (12.4) is arranged to disengage from the plunger (9) on translation of the needle sheath (11) and sheath linkage (12) in distal direction (D) from the initial position.
Auto-injector (1) according to claim 6,characterized in that the activating means comprises a trigger button (10) arranged to be engaged with the plunger (9) so as to prevent rotation and thus translation of the plunger (9) prior to operation and wherein the trigger button (10) is arranged to be disengaged from the plunger (9) when operated.
Auto-injector (1) according to one of the claims 6 or 7,characterized in that the angles and widths of the ramps (9.6, 2.5, 2.7, 7.2) are matched so as to rotate the plunger (9), the syringe (3) and the syringe carrier (7) as a single body.
Auto-injector (1) according to one of the claims 5 to 8,characterized in that rotation of the syringe (3) by the ramps (9.6, 2.5, 2.7, 7.2) stops before the needle (4) protrudes from the proximal end (P) of the housing (2) or from the needle sheath (11).
Auto-injector (1) according to one of the claims 5 to 9,characterized in that at least one resilient latch (7.5) is arranged on the circumference of the syringe carrier (7) for flexing outwards into a respective recess (2.9) in the housing (2) when the syringe carrier (7), syringe (3) and needle (4) have been translated in proximal direction (P) and the needle (4) has reached a predefined injection depth.
Auto-injector (1) according to one of the claims 5 to 10,characterized in that at least one inwardly biased resilient snap (2.10) is arranged near the proximal end (P) in the housing (2) for preventing the needle sheath (11) from translating in distal direction (D) after having been translated into a proximal position for covering the needle (4).
Method for operating a needle safety arrangement for protecting a hollow injection needle (4) of a syringe (3) after an injection, the needle safety arrangement comprising:
- a needle sheath (11) having essentially the shape of a hollow cylinder arranged to surround the needle (4), the needle sheath slidable in longitudinal direction with respect to the syringe (3) and biased in proximal direction (P),
- a sheath linkage (12), slidable in longitudinal direction,
- a syringe carrier (7) for holding the syringe (3), the syringe (3) and syringe carrier (7) arranged for joint axial translation and rotation relative to the needle sheath (11),
wherein the sheath linkage (12) comprises means (12.3) for restricting translation in proximal direction (P) with respect to the syringe (3) by abutting against the syringe carrier (11), the method comprising:
- restricting translation of the sheath linkage (12) in proximal direction (P) in an initial state, wherein the sheath linkage (12) is latched to the needle sheath (11) for joint axial translation,
- rotating the syringe carrier (7), thereby de-latching the needle sheath (11) from the sheath linkage (12) by means of at least one cam (7.4) arranged on the circumference of the syringe carrier (7) so as to release the needle sheath (11) for being translated in proximal direction (P) and cover the needle (4).
Method according to claim 12,characterized in that in the initial position at least one spline formed by the latched needle sheath (11) and sheath linkage (12) is engaged in a respective slot (7.3) on the circumference of the syringe carrier (7) so as to prevent rotation of the syringe carrier, wherein the needle sheath (11) is translated in distal direction (D) from the initial position thereby disengaging the spline from the slot (7.3) for allowing rotation of the syringe carrier (7).
Method according to one of the claims 12 or 13,characterized in that the syringe carrier (7) is rotated by at least one ramp (2.6, 7.1) on translation from an initial distal position in proximal direction (P) so as to de-latch the needle sheath (11) from the sheath linkage (12).
Method according to one of the claims 12 to 14,characterized in that the needle sheath (11) comprises at least one sheath leg (11.1) extending from the needle sheath (11) in distal direction (D), wherein the sheath linkage (12) comprises at least one linkage leg (12.1), wherein the spline consists of a distal end portion of the sheath leg (11.1) and a proximal end portion of the linkage leg (12.1), wherein a rib protrudes inwards from the distal end of the sheath leg (11.1), the rib (11.2) having an aperture for accommodating the proximal end of the linkage leg (12.1), wherein the proximal end portion of the linkage leg (12.1) comprises an inwardly biased resilient tongue (12.2) connected to the linkage leg (12.1) at one end, wherein for latching the needle sheath (11) to the sheath linkage (12) the proximal end of the linkage leg (12.1) is put through the aperture in the rib (11.2) until a free end of the tongue (12.2) engages proximally behind the rib (11.2) so as to prevent removal of the proximal end portion of the linkage leg (12.1) through the aperture in the rib (11.2), wherein for decoupling the needle sheath (11) from the sheath linkage (12) the tongue (12.2) is flexed outwards by the cam (7.4) on rotation of the syringe carrier (7) so as to align it with the linkage leg (12.1) and allow the linkage leg (12.1) to be at least partially pulled out of the aperture in the rib (11.2).